The first week (most commonly day - days) just after a new month starts you'll get the seasonal rewards. These include 60 uncommon ninja frags and 30 rare ninja frags. You will also get seal fragments (up to 30) and 12ranked arena points. These rewards can be collected the moment you'd like as they won't be insta added to your inventory.

You start over from Genin Rank next season (if you use the 12 points you'll get some ranks, but most people wait till 48 ranked arena points to insta 60 and be six paths), and must climb again to six paths to get the best rewards. If you fail, you'll get some rewards based on your rank and it won't reset next month. If you achieve 6paths, the cycle continues.

That *s. Nice to know, ty